JP6219474B2 - Wireless communication system using multiple transmission / reception points - Google Patents

Description

  The present invention relates to a wireless communication system, and more particularly, to a wireless communication system using multiple transmission / reception points that can be applied to a wireless communication system having a plurality of transmission / reception points geographically separated from each other in a cell.

The wireless communication system has an extremely high data transmission rate together with the wired communication system. This tendency to keep pace is fourth generation mobile communication system ^{3GPP (3 rd Generation Project Partnership)} LTE (Long Term Evolution) -Advanced system, cooperative multi-point (CoMP: Coordinated MultiPoint, hereinafter referred to 'CoMP' ) We are promoting standardization of transmission and reception methods.

  The CoMP transmission / reception method indicates a transmission / reception operation between two or more points (site, cell, base station, distributed antenna, etc.) and one or more terminals. The CoMP transmission / reception method includes uplink CoMP transmission and downlink CoMP. It can be divided into transmission.

  Uplink CoMP transmission is a transmission method in which a predetermined terminal transmits a signal at a plurality of points geographically separated from each other, and the signals received from the terminal are jointly processed at the plurality of points. With uplink CoMP transmission, the terminal does not need to know what network node has transmitted the signal or what processing has been performed on the received signal, and what downlink signaling is associated with the uplink transmission. You only need to know if it is provided. Therefore, uplink CoMP transmission can be introduced without significant changes to the radio interface standard.

  Downlink CoMP transmission is a method in which a plurality of points geographically distant from each other transmits a signal to one or more terminals in cooperation with each other. In 3GPP TR 36.814, a downlink CoMP category is jointly processed ( JP (Joint Processing) and Cooperative Beamforming / Cooperative Scheduling (CB / CS: Coordinated Beam forming / Coordinated Scheduling), and Joint Processing (JP) is further divided into multiple points (PinsCH) by PDSCH. ) Joint transmission (JT: Joint Transmission) when transmission is performed simultaneously. Dynamic point selection a case in which the PDSCH transmission in (one point): are classified into (DPS Dynamic Point Selection).

  Joint transmission (JT) is a distributed antenna concept in which data can be used at each transmission point in a CoMP cooperating set (CoMP cooperating set). It is characterized by very fluid performance due to errors and the like.

  The dynamic point selection (DPS) method is a method of performing PDSCH transmission at one point in the CoMP cooperating set at a specific moment, and the transmission point can be changed dynamically, and performance is degraded due to feedback delay. can do.

  The cooperative beamforming / cooperative scheduling (CB / CS) method is a method of transmitting data to a terminal only at a serving point at a specific moment, and is a passive method for avoiding interference between transmission points. Therefore, when a large capacity increase cannot be expected, and user scheduling / beamforming needs to exchange information between different base stations, cooperation between points corresponding to CoMP cooperating set requires backhaul. Can be used.

  On the other hand, in the 3GPP LTE standard Release-8, Release-9, and LTE-Advanced standard Release-10, it is common that all transmission points have different physical layer cell IDs (Physical Cell Identity). Accordingly, if a transmission method using multiple points as described above is applied to the standard, transmission using multiple points is performed in an environment where each transmission point has its own cell coverage. It can be seen.

  Therefore, the above-mentioned conventional standard has a problem that a plurality of points belong to the same cell and cannot be applied in a multi-point transmission environment having the same physical layer cell ID.

  In order to overcome the inconveniences described above, an object of the present invention is to multiplex transmission / reception that enables communication using a plurality of points in a network environment in which a plurality of points belong to the same cell and have the same physical layer cell ID. It is to provide a wireless communication system using points.

  In order to achieve the above object, a wireless communication system using multiple transmission / reception points according to an aspect of the present invention is a wireless communication system including a first transmission / reception point and at least one second transmission / reception point belonging to the same cell. The first transmission / reception point has a wider transmission area than the at least one second transmission / reception point, and the first transmission / reception point and the at least one second transmission / reception point have the same physical layer cell ID (Physical Cell Identity). Is used to generate a downlink transmission signal.

  Here, the first transmission / reception point can transmit a synchronization signal and a cell-specific reference signal corresponding to the physical layer cell ID, and the at least one second transmission / reception point is synchronized with the first transmission / reception point. The signal may not be transmitted using the radio resource used to transmit the signal and the cell-specific reference signal.

  Here, the first transmission / reception point and the at least one second transmission / reception point transmit a CSI reference signal (Channel State Information Reference Signal) generated using the physical layer cell ID, and the CSI reference signal The setting and the mapping of radio resources corresponding thereto can be performed so that the first transmission / reception point and the at least one second transmission / reception point are different from each other.

  Here, the first transmission / reception point and the at least one second transmission / reception point generate a PMCH (Physical Multicast Channel) or an MBSFN reference signal (Multicast-Broadcast Single Frequency Reference) using the physical layer cell ID. The PMCH or MBSFN reference signal can be transmitted using the same radio resource.

  Here, the first transmission / reception point may be a PBCH (Physical Broadcast Channel), a PCFICH (Physical Control Format Channel Indicator), a PDCCH (Physical Downlink Channel), or a PDCCH (Physical Downlink Channel). An indicator channel or a position reference signal can be transmitted, and the at least one second transmission / reception point transmits the PBCH, PCFICH, PDCCH, PHICH, or position reference signal. Radio resources used for The signals use can be configured not to transmit.

  Here, the first transmission / reception point and the at least one second transmission / reception point may simultaneously transmit at least one of the PBCH, PCFICH, PDCCH, PHICH, and position reference signal using the same radio resource. it can.

  A wireless communication system using multiple transmission / reception points according to another aspect of the present invention includes a base station, a first transmission / reception point belonging to the same cell operated by the base station, and at least one second transmission / reception point. In the system, the first transmission / reception point has a wider transmission area than the at least one second transmission / reception point, and the first transmission / reception point and the at least one second transmission / reception point are virtual cells allocated to a terminal. A signal to be transmitted to the terminal is generated using the ID.

  Here, the first transmission / reception point can transmit a PDSCH (Physical Downlink Shared Channel) generated using the virtual cell ID to the terminal, and the at least one second transmission / reception point is transmitted by the terminal. When the CSI reference signal (Channel State Information Reference Signal) and the terminal-specific reference signal (UE-specific Reference Signal) are used, the terminal-specific reference signal generated using the PDSCH and the virtual cell ID is transmitted to the terminal. can do.

  Here, the first transmission / reception point and the at least one second transmission / reception point may simultaneously transmit the PDSCH to the terminal when the terminal uses a cell-specific reference signal (Cell-specific Reference Signal).

  Here, the first transmission / reception point and the at least one second transmission / reception point are determined using the virtual cell ID for radio resource mapping of a signal transmitted to the terminal through an antenna port 5. Wireless resources can be used.

  Here, the first transmission / reception point and the at least one second transmission / reception point may generate a physical channel and a position reference signal that perform a PDCCH and a PHICH function using the virtual cell ID, respectively. The physical channels that perform the PDCCH and PHICH functions can be transmitted using radio resources that the first transmission / reception point can use for PDSCH transmission.

  The base station forms a cooperation point set composed of at least one transmission / reception point that performs cooperative transmission to the terminal based on channel state information reported from the terminal, and is included in the cooperation point set. One transmission / reception point can transmit a PDSCH generated using the virtual cell ID of the terminal to the terminal using the same radio resource, and a terminal-specific reference signal for demodulation of the terminal can be transmitted. It can be transmitted to the terminal simultaneously with PDSCH.

  A radio communication system using multiple transmission / reception points according to still another aspect of the present invention includes a base station, a first transmission / reception point belonging to the same cell operated by the base station, and at least one second transmission / reception point. In the communication system, the base station includes CSI reference signal measurement information including a CSI reference signal (Channel State Information Reference Signal) transmitted at at least one transmission / reception point among the first transmission / reception point and the at least one transmission / reception point. At least one CSI that the terminal must measure based on the received measurement result after receiving the measurement result for the CSI reference signal corresponding to the CSI reference signal measurement information from the terminal. Reference signal To transmit the turn to the terminal.

  A radio communication system using multiple transmission / reception points according to still another aspect of the present invention includes a base station, a first transmission / reception point belonging to the same cell operated by the base station, and at least one second transmission / reception point. In the communication system, after at least one terminal generates an uplink channel and a reference signal using different virtual cell IDs allocated from the base station, the first transmission / reception point and the at least one second transmission / reception It can be transmitted to at least one transmission / reception point.

  Here, each of the at least one terminal uses a different virtual cell ID assigned to each of the PUSCH (Physical Uplink Shared Channel), PUCCH (Physical Uplink Control Channel), DMRS (Demodulation Reference Signal), and DMRS (Demodulation Reference Signal). Signal) can be generated.

  According to the wireless communication system using multiple transmission / reception points as described above, downlink communication using a plurality of transmission / reception points is performed in a communication environment in which a plurality of transmission / reception points belonging to the same cell have the same physical layer cell ID. Providing a physical channel transmission method and a reference signal transmission method, introducing a virtual cell ID, and providing a method for transmitting a physical channel and a reference signal, while minimizing changes to existing standards, Enables efficient transmission using transmission / reception points.

  Further, by providing a cooperative transmission method using a plurality of transmission / reception points belonging to the same cell, it is possible to improve downlink communication efficiency.

  Also, a virtual cell ID is introduced for uplink communication using a plurality of transmission / reception points in a communication environment in which a plurality of transmission / reception points belonging to the same cell have the same physical layer cell ID, and an uplink physical channel and reference By providing a signal transmission method, uplink communication efficiency can be improved while minimizing changes to existing standards.

FIG. 1 is a conceptual diagram illustrating a wireless communication system using multiple transmission / reception points according to an embodiment of the present invention. FIG. 2 illustrates a downlink communication method of a wireless communication system using multiple transmission / reception points according to an embodiment of the present invention. FIG. 3 is a flowchart illustrating an example of using a virtual cell ID in downlink transmission using multiple transmission / reception points according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating a CSI reference signal based measurement process in a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention. FIG. 5 is a flowchart illustrating a process of performing cooperative multipoint transmission in a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention.

  While the invention is susceptible to various modifications, and various embodiments thereof, specific embodiments are shown by way of example in the drawings and are described in detail.

  However, this should not be construed as limiting the invention to any particular embodiment, but should be understood to include all modifications, equivalents or alternatives that fall within the spirit and scope of the invention.

  The terminology used in the present application is merely used to describe particular embodiments, and is not intended to limit the present invention. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. In this application, terms such as “including” or “having” are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification. It should be understood that the existence or additional possibilities of one or more other features or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

  Unless defined differently, all terms used herein, including technical or scientific terms, are identical to those commonly understood by those having ordinary skill in the art to which this invention belongs. It has meaning. Terms such as those defined in commonly used dictionaries shall be construed as having a meaning consistent with the meaning possessed in the context of the related art, and unless otherwise explicitly defined in this application, Is not interpreted as a formal or overly formal meaning.

A “terminal” used in the present application includes a mobile station (MS), a mobile terminal (MT), a user terminal, user equipment (UE: User Equipment), a user terminal (UT: User Terminal), and a wireless terminal. , Access Terminal (AT), Subscriber Unit (Subscriber
(Unit), Subscriber Station (SS), wireless device (Wireless device), wireless communication device, wireless transmit / receive unit (WTRU), mobile node, mobile, or other terminology Can do.

  In addition, the “base station” used in the present application generally refers to a fixed point where the terminal communicates with the base station (Base Station), Node-B (Node-B), eNode-B (eNode). -B), BTS (Base Transceiver System), and other terms such as an access point.

  In addition, a “point” or “transmission / reception point” used in the present application includes at least one transmission and reception antenna, and is connected to the base station by an optical fiber, a microwave, etc., and exchanges information with the base station. It can be referred to as an RRH (Remote Radio Head), an RRU (Remote Radio Unit), a site, a distributed antenna, or the like.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same reference numerals are used for the same constituent elements in the drawings, and redundant description of the same constituent elements is omitted.

  FIG. 1 is a conceptual diagram illustrating a wireless communication system using multiple transmission / reception points according to an embodiment of the present invention.

  Referring to FIG. 1, a wireless communication system according to an embodiment of the present invention may include a base station 110, a wide area transmission / reception point 130, and a narrow area transmission / reception point 150, and the wide area transmission / reception point 130 and at least one narrow area transmission / reception point. The point 150 can be located in the cell 111 operated by the base station 110. The wide-area transmission / reception point 130 forms a wide transmission area 131 using high transmission power, and the narrow-area transmission / reception point 150 uses transmission power lower than that of the wide-area transmission / reception point 130. A transmission region 151 narrower than 131 can be formed.

  Further, as shown in FIG. 1, the transmission area 151 of each of the plurality of narrow area transmission / reception points 150 can be arranged to be included in the transmission area 131 of the wide area transmission / reception point 130, The point is connected to the wide-area transmission / reception point 130 wirelessly or by wire, and can exchange control information and / or data. The plurality of narrow-area transmission / reception points 150 and wide-area transmission / reception points 130 are connected to the base station 110 through optical fibers, microwaves, and the like, and can exchange information with the base station 110. Information can also be exchanged.

  In the wireless communication system as shown in FIG. 1, two physical layer cell ID (PCI: Physical Cell Identity) allocation methods for the transmission / reception points 130 and 150 can be considered.

  The first physical layer cell ID assignment method is a method in which all the transmission / reception points 130 and 150 are assigned so as to have different physical layer cell IDs, and each transmission / reception point 130 and 150 has its own cell area (cell coverage). Will be configured. The 3GPP LTE Release-8, Release-9, and LTE-Advanced Release-10 standards can be applied to the first scheme.

  The second physical layer cell ID assignment method is a method of assigning the same physical layer cell ID to all the transmission / reception points 130 and 150 belonging to the same cell. The existing 3GPP LTE or LTE-Advanced standard described above is the second method. This method cannot be applied.

  In a wireless communication system using multiple transmission / reception points according to an embodiment of the present invention, when all transmission / reception points belong to the same cell and are assigned the same cell ID, downlink communication for transmission / reception point communication is performed. A method and an uplink communication method are provided. Hereinafter, in the embodiment of the present invention, it is assumed that communication between the base station and the terminal conforms to the 3GPP LTE-Advanced Release-10 standard.

  First, a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention will be described.

  FIG. 2 illustrates a downlink communication method of a wireless communication system using multiple transmission / reception points according to an embodiment of the present invention.

  Hereinafter, a downlink communication method of a wireless communication system using multiple transmission / reception points according to an embodiment of the present invention will be described in detail for each downlink physical channel and reference signal with reference to FIG.

Frame Synchronization In a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, it is assumed that radio frames transmitted by all transmission / reception points are synchronized with each other. Further, since all radio frames are synchronized, it is assumed that the subframes (subframes) and OFDM symbols (symbols) constituting the radio frames are also synchronized.

Synchronization signal and cell-specific reference signal A method of transmitting a synchronization signal and a cell-specific reference signal in a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention can be broadly described. Two can be considered. Here, the cell-specific reference signal is used for the terminal to estimate the downlink channel and to demodulate the received signal based on the downlink channel.

  In the first method, a specific transmission / reception point (for example, a wide-area transmission / reception point) among the transmission / reception points transmits a synchronization signal and a cell-specific reference signal corresponding to the physical layer cell ID using a transmission antenna provided by itself. The transmission / reception point (for example, the narrow-area transmission / reception point) is a method in which the specific transmission / reception point does not transmit a signal using radio resources used to transmit a synchronization signal and a cell-specific reference signal.

  The second method is a method in which all the transmission / reception points simultaneously transmit the synchronization signal corresponding to the physical layer cell ID and the cell-specific reference signal using the same radio resource.

  Here, the radio resource means a time-frequency space resource element defined in 3GPP LTE and LTE-Advanced standards.

CSI Reference Signal Each transmission / reception point can transmit its own CSI reference signal (Channel State Information Reference Signal). Here, the CSI reference signal is a reference signal used by the terminal to measure the quality of the downlink channel, and the setting of the CSI reference signal transmitted by each transmission / reception point and the mapping of radio resources corresponding thereto are as follows: Can be different from each other. Also, the CSI reference signal sequence used when each transmission / reception point transmits its own CSI reference signal can be generated using the physical layer cell ID.

Physical Muticast Channel or PMCH
Each transmission / reception point belonging to the same cell can transmit the PMCH using the same radio resource. Here, PMCH means a physical channel used for MBSFN (Multicast-Broadcast Single Frequency Network) operation.

Physical Broadcast Channel or PBCH
A PBCH is a physical channel used to transmit system information necessary for a terminal to connect to a network. In a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, the PBCH Two methods of transmission are provided.

The first method is a method in which a wide-area transmission / reception point transmits PBCH. Here, the wide-area transmission / reception point is a bit unit scrambling (bit-level) during PBCH transmission.
In order to generate a scrambling sequence for scrambling, the physical layer cell ID is used as in the scheme defined in the LTE and LTE-Advanced standards. On the other hand, at least one narrow area transmission / reception point does not transmit a signal using a radio resource used by the wide area transmission / reception point to transmit the PBCH.

  The second method is a method in which all transmission / reception points belonging to the same cell simultaneously transmit the same PBCH using the same radio resource. Here, each transmission / reception point uses a physical layer cell ID as in the scheme defined in the LTE and LTE-Advanced standards for generating a scrambling sequence for bit-unit scrambling during PBCH transmission.

Physical Control Format Indicator Channel or PCFICH
The PCFICH is a downlink physical channel used to provide information necessary for decoding a PDCCH (Physical Downlink Control Channel) to a UE, and uses multiple transmission / reception points according to an embodiment of the present invention. In the downlink communication method, two methods of transmitting PCFICH are provided.

  The first method is a method in which a wide-area transmission / reception point transmits PCFICH. Here, the wide area transmission / reception point uses the physical layer cell ID as in the method defined in the LTE and LTE-Advanced standards for radio resource mapping for PCFICH transmission and generation of a scrambling sequence for bit unit scrambling. use. On the other hand, at least one narrow area transmission / reception point does not transmit a signal using a radio resource used by the wide area transmission / reception point to transmit PCFICH.

  The second method is a method in which all transmission / reception points belonging to the same cell simultaneously transmit the same PCFICH using the same radio resource. Here, each transmission / reception point uses a physical layer cell ID as in a method defined in the LTE and LTE-Advanced standards for generating a scrambling sequence for bit-unit scrambling during PCFICH transmission.

Physical Downlink Control Channel or PDCCH
The PDCCH is a scheduling allocation (scheduling) required for the terminal to receive PDSCH (Physical Downlink Shared Channel).
It is a downlink physical channel used to transmit downlink control information such as assignment and information such as scheduling grant for PUSCH (Physical Up and Shared Channel) transmission of the terminal.

  The downlink communication method using multiple transmission / reception points according to an embodiment of the present invention provides two methods for transmitting the PDCCH.

  The first method is a method in which a wide-area transmission / reception point transmits PDCCH. Here, the wide area transmission / reception point uses the physical layer cell ID as in the method defined in the LTE and LTE-Advanced standards for mapping radio resources and generating a scrambling sequence for bit unit scrambling during PDCCH transmission. To do. On the other hand, at least one narrow area transmission / reception point does not transmit a signal using a radio resource used by the wide area transmission / reception point to transmit the PDCCH.

  The second method is a method in which all transmission / reception points belonging to the same cell simultaneously transmit the same PDCCH using the same radio resource. Here, each transmission / reception point uses a physical layer cell ID as in a method defined in the LTE and LTE-Advanced standards for generating a scrambling sequence for bit-unit scrambling during PDCCH transmission.

Physical Hybrid ARQ Indicator Channel or PHICH
PHICH is a downlink physical channel used to transmit HARQ acknowledgment for notifying a terminal whether or not retransmission of a transmission block (transport block) can be performed.

  In a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, two methods for transmitting PHICH are provided.

  The first method is a method in which a wide-area transmission / reception point transmits PHICH. Here, the wide area transmission / reception point uses the physical layer cell ID as in a method defined in the LTE and LTE-Advanced standards for generating a cell-specific scrambling sequence at the time of PHICH transmission. On the other hand, at least one narrow area transmission / reception point does not transmit a signal using a radio resource used by the wide area transmission / reception point to transmit PHICH.

  The second method is a method in which all transmission / reception points belonging to the same cell simultaneously transmit the same PHICH using the same radio resource. Here, each transmission / reception point uses a physical layer cell ID as in the scheme defined in the LTE and LTE-Advanced standards for generating a scrambling sequence for bit-unit scrambling during PHICH transmission.

MBSFN reference signal MBSFN Reference Signal is a reference signal used to measure a composite channel of each transmission / reception point at which a terminal transmits MBSFN data. In the downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, each transmission / reception point can transmit an MBSFN reference signal. Here, the radio resource and sequence used by each transmission / reception point to transmit the MBSFN reference signal may be the same.

A position reference signal (PRS: Positioning Reference Signal) is a signal transmitted by a base station and / or a transmission / reception point to effectively perform position estimation of a terminal. The terminal measures a position reference signal. Base station and / or by calculating its position based on the measured value and transmitting it to the base station and / or transmission / reception point or transmitting the information necessary to calculate the position of the terminal The transmission / reception point determines the position of the terminal.

  In a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, two methods for transmitting a position reference signal are provided.

  The first method is a method in which a wide-area transmission / reception point transmits a position reference signal. Here, the wide area transmission / reception point uses the physical layer cell ID for the sequence generation of the position reference signal and the radio resource mapping of the position reference signal as in the method defined in the LTE-Advanced standard. On the other hand, at least one narrow area transmission / reception point does not transmit a signal using a radio resource used by the wide area transmission / reception point to transmit a position reference signal.

  The second method is a method in which all transmission / reception points belonging to the same cell simultaneously transmit the same position reference signal using the same radio resource. Here, each transmission / reception point uses a physical layer cell ID as in the method defined in the LTE-Advanced standard for generating a sequence of a location reference signal and mapping radio resources of the location reference signal.

In a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, a plurality of transmission / reception points are connected to the same cell for a terminal supporting LTE-Advanced Release-11 or a later standard. A virtual cell ID is introduced in the network arrangement environment to which it belongs.

  In the LTE-Advanced Release-10 standard, a reference signal sequence used for a UE-specific reference signal (UE-specific Reference Signal) is a pseudo-random sequence, and an initialization value used for generating a pseudo-random sequence is: It is defined as different depending on the physical layer cell ID. Therefore, cells having different physical layer cell IDs use different pseudo-random sequences as reference signal sequences. The reason why different cells use different physical layer cell IDs and generate different pseudo-random sequences in this way is to mitigate inter-cell interference (Inter-Cell Interference). In particular, in the case of reference signals corresponding to antenna ports 7, 8, 9, 10, 11, 12, 13, and 14, all cells use the same radio resource, so interference due to reference signals transmitted from neighboring cells. In order to relax the signal, it is necessary to use different reference signal sequences between adjacent cells.

  On the other hand, as shown in FIG. 1, when a plurality of transmission / reception points transmit different data using the same resource in a transmission environment using multiple transmission / reception points, signals transmitted by adjacent transmission / reception points are transmitted. In order to mitigate interference, it is necessary to use different reference signal sequences between transmission and reception points.

  As described above, in order to use reference signals with different transmission / reception points, different initialization values should be used when each transmission / reception point generates a pseudo-random sequence used for generating a terminal-specific reference signal sequence. Is preferred.

  FIG. 3 is a flowchart illustrating an example of using a virtual cell ID in downlink transmission using multiple transmission / reception points according to an embodiment of the present invention.

  Referring to FIG. 3, first, the base station 110 notifies the virtual cell ID for each of the terminals 171 and 173 (step S310).

  Thereafter, the base station 110 applies the virtual cell ID instead of the physical layer cell ID, generates a pseudo random sequence to generate a reference signal sequence (step S320), and uses the generated reference signal sequence to each terminal. After generating the unique reference signals 171 and 173 (step S330), the generated unique reference signals of the terminals 171 and 173 are transmitted to the terminals (step S340). Here, the virtual cell ID may be assigned a different value for each terminal.

  Each terminal 171 and 173 generates a reference signal sequence using the virtual cell ID allocated from the base station 110 (step S350), and detects a terminal-specific reference signal using the generated reference signal sequence (step S350). S360).

  In the case of PDSCH transmission, the base station may generate a pseudo-random sequence by applying a virtual cell ID instead of a physical layer cell ID to generate a scrambling sequence used for bit unit scrambling of each codeword. it can. In this case, the terminal generates a scrambling sequence using the virtual cell ID assigned from the base station, and then performs PDSCH detection using the generated scrambling sequence.

  Hereinafter, a method of using a virtual cell ID in a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention will be described in more detail.

Physical Downlink Shared Channel or PDSCH
In the case of a terminal that supports the LTE or LTE-Advanced Release-8 / 9/10 standard, the scrambling sequence used for the bit unit scrambling of each codeword is a pseudo-random sequence using the physical layer cell ID. Generate a scrambling sequence.

  In the case of a terminal that supports LTE-Advanced Release-11 and subsequent standards, a scrambling sequence is generated using a virtual cell ID instead of a physical layer cell ID for a terminal to which a virtual cell ID is assigned. To do.

  Alternatively, when a terminal supporting LTE-Advanced Release-11 and subsequent standards cannot be assigned a virtual cell ID, a scrambling sequence can be generated using the physical layer cell ID. For example, in the process of performing random access to connect the terminal to the network, since the terminal is not yet assigned a virtual cell ID, the base station applies the physical layer cell ID to the response and message transmission for the random access of the terminal. Then, the scrambling sequence is generated, and then the bit word scrambling of the codeword encoded using the generated scrambling sequence is performed.

  The downlink communication method using multiple transmission / reception points according to an embodiment of the present invention provides two methods for transmitting PDSCH.

  The first method is a method in which a wide-area transmission / reception point transmits PDSCH. The terminal uses a cell-specific reference signal (CRS) according to a transmission mode (transmission mode) or receives a UE-specific reference signal (UE-specific Reference Signal) from a wide-area transmission / reception point. The received PDSCH can be demodulated.

  Meanwhile, at least one narrowband transmission / reception point uses a CSI reference signal (CSI-RS) to acquire channel estimation and CQI (Channel Quality Indicator) information, and performs data demodulation using a terminal-specific reference signal. When the transmission mode to be performed is set, the PDSCH and the terminal-specific reference signal can be transmitted to the terminal.

  Alternatively, when at least one narrowband transmission / reception point is set to a transmission mode in which a terminal obtains channel estimation and CQI information using a cell-specific reference signal (CRS) and performs data demodulation, PDSCH is not transmitted. This is because in the first method, at least one narrow-band transmission / reception point does not transmit a cell-specific reference signal (CRS) to the terminal.

  In the second method, when a terminal acquires a channel estimation and CQI information using a CSI reference signal and is set to a transmission mode in which data demodulation is performed using a terminal-specific reference signal, each terminal belonging to the same cell is used. In this method, the transmission / reception point transmits the PDSCH and the terminal-specific reference signal to the terminal.

  Alternatively, when channel estimation and CQI information is acquired using a cell-specific reference signal and the transmission mode is set to perform data demodulation, all the transmission / reception points belonging to the same cell simultaneously transmit the same PDSCH to the terminal. To do.

Terminal Specific Reference Signal Each transmission / reception point belonging to the same cell can transmit a terminal specific reference signal together with PDSCH.

  Here, each transmission / reception point generates and transmits a terminal-specific reference signal sequence using a virtual cell ID instead of a physical layer cell ID to a terminal to which a virtual cell ID is assigned, and receives the received terminal. Detects a terminal-specific reference signal using a reference signal sequence generated using the assigned virtual cell ID.

  Each transmission / reception point generates and transmits a terminal-specific reference signal sequence using a virtual cell ID instead of a physical layer cell ID to a terminal to which a virtual cell ID is assigned. The reference signal sequence is generated using the virtual cell ID, and the terminal-specific reference signal is detected.

  In addition, each transmission / reception point uses a virtual resource mapping of a signal (for example, a terminal-specific reference signal) transmitted through an antenna port (Antenna Port) 5 for a terminal to which a virtual cell ID is assigned instead of a physical layer cell ID. The radio resource determined using the cell ID is used.

  Alternatively, each transmission / reception point generates and transmits a terminal-specific reference signal sequence using a physical layer cell ID to a terminal to which a virtual cell ID is not assigned, and the terminal that has received this transmits the physical layer cell ID. A terminal-specific reference signal is detected using a reference signal sequence generated by using the reference signal sequence.

  In addition, each transmission / reception point uses a radio resource determined using the physical layer cell ID for radio resource mapping for a signal transmitted through the antenna port 5 to a terminal to which a virtual cell ID is not assigned.

Introducing RRH-PDCCH and RRH-PHICH In the downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, each transmission / reception point belonging to the same cell is defined as PDCCH and PHICH defined in LTE or LTE-Advanced standard. Introduce new physical channels that can perform each of the functions.

  In one embodiment of the present invention, a new physical channel capable of performing the PDCCH function is referred to as RRH-PDCCH, and a new physical channel capable of performing the PHICH function is referred to as RRH-PHICH.

  Each transmission / reception point belonging to the same cell transmits the RRH-PDCCH and RRH-PHICH and the terminal-specific reference signal together so that the terminal can demodulate the RRH-PDCCH and RRH-PHICH. Here, the RRH-PDCCH and the RRH-PHICH can be transmitted using a part of radio resources that can be used by the wide-area transmission / reception point for PDSCH transmission.

  Each transmission / reception point can use the virtual cell ID for mapping of RRH-PDCCH and RRH-PHICH to radio resources and generating a scrambling sequence for bit-based scrambling.

Introducing RRH-PRS In the downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, a new reference signal is introduced in order to improve the accuracy of the location of the terminal. In the present invention, the above-described new reference signal is referred to as RRH-PRS.

  A plurality of transmission / reception points belonging to the same cell can transmit RRH-PRS to confirm the location of the terminal. Here, each transmission / reception point can use a virtual cell ID for RRH-PRS sequence generation and RRH-PRS radio resource mapping.

CSI Reference Signal Based Measurement In a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention, a CSI reference signal (CSIRS) based measurement is performed.

  FIG. 4 is a flowchart illustrating a CSI reference signal based measurement process in a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention.

  Referring to FIG. 4, first, the base station 110 transmits CSI reference signal measurement information for each terminal (step S410). Here, the CSI reference signal measurement information may include setting information corresponding to all or a part of the CSI reference signal transmitted at each transmission / reception point, and the setting according to a predefined mapping rule. It is set so that terminal 170 can grasp the radio resource pattern information of the time-frequency space of the CSI reference signal from the information.

  The terminal 170 that has received the information for measuring the CSI reference signal transmitted from the base station 110 measures the CSI reference signal included in the CSI reference signal measurement information (step S420), and the measurement result is transmitted to the base station. 110 (step S430).

  The base station 110 determines a CSI reference signal pattern or CSI reference signal pattern that the terminal 170 must measure based on the measurement result received from the terminal 170 (step S440), and determines the determined CSI reference signal pattern or CSI reference signal. The pattern is transmitted to the terminal 170 (step S450).

The terminal 170 acquires CSI for link adaptation using the CSI reference signal pattern or the CSI reference signal pattern received from the base station 110 (step S460), and reports the acquired CSI to the base station 110. (Step S470).
The base station 110 performs link adaptation based on the CSI received from the terminal 170 (step S480).

Cooperative transmission of multiple transmission / reception points In a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention , cooperative multiple transmission / reception point transmission in which a base station transmits data or control information to a terminal using multiple transmission / reception points. It can be performed.

  Hereinafter, a set of a plurality of transmission / reception points that perform cooperative transmission to a terminal in a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention is referred to as a “cooperation point set”.

  FIG. 5 is a flowchart illustrating a process of performing cooperative multipoint transmission in a downlink communication method using multiple transmission / reception points according to an embodiment of the present invention.

  First, the base station 110 receives channel state information from each terminal 170 (step S510).

  Thereafter, the base station 110 determines a cooperation point set for performing cooperative multiplex transmission / reception point transmission to the terminal 170 based on the received channel state information (step S520). That is, the cooperation point set can be set differently for each terminal 170 depending on the channel environment of each terminal 170.

  A plurality of transmission / reception points 151 and 153 included in a cooperation point set that performs cooperative multiple transmission / reception point transmission to the terminal 170 generate a transmission signal for transmitting the same data to the terminal 170 using the same radio resource. After (step S530), the generated transmission signal and the terminal-specific reference signal for demodulating terminal 170 are transmitted to terminal 170 together (step S540).

  Here, a plurality of transmission / reception points that perform cooperative multiplex transmission / reception point transmission must simultaneously transmit the terminal-specific reference signal, and must use the same reference signal sequence. For this purpose, a plurality of transmission / reception points that perform cooperative multiplex transmission / reception point transmission transmit the PDSCH generated using the virtual cell ID notified to the terminal by the base station and the terminal-specific reference signal sequence.

  Hereinafter, an uplink communication method using multiple transmission / reception points according to an embodiment of the present invention when all transmission / reception points belong to the same cell and the same cell ID is assigned will be described.

  In an uplink communication method using multiple transmission / reception points according to an exemplary embodiment of the present invention, a UE can transmit a PUSCH (Physical Uplink Channel), a PUCCH (Physical Uplink Channel), and a PRACH (Physical Random Channels) through the uplink. Demodulation Reference Signal (SRS) and SRS (Sounding Reference Signal) can be transmitted.

In the case of PUSCH, PUCCH, DMRS, and SRS, according to the LTE Release-8 / 9 and LTE-Advanced Release-10 standards, signals are generated using physical layer cell IDs for the following functions. Become.
-PUSCH scrambling sequence generation -Cell-specific symbol unit cyclic shift hopping (Cell-Specific Symbol-Level) of PUCCH formats 1, 1a, 1b, 2, 2a, 2b
Cyclic Shift Hopping)
-PUCCH format 3 bit unit scrambling sequence generation, cell-specific SC-FDMA (Single Carrier Division Frequency Access) symbol unit cyclic shift hopping (Cell-Specific Cyclic Shift Hopping), cell unit SC-Scrambled Base sequence hopping (Base-Sequence Hopping), sequence group hopping (Sequence-Group Hopping) and sequence hopping (Sequence Hopping) of SRS and DM RS
-PUSCH DM RS reference signal sequence generation, cell-specific slot unit cyclic shift hopping (Cell-Specific Slot-Level Cyclic Shift Hopping)
-PUCCH DM RS cell-specific cyclic shift hopping (Cell-Specific Symbol-Level Cyclic Shift Hopping)

  Since the terminal supporting the LTE Release-8 / 9/10 standard generates a signal according to the support standard, the terminal generates and transmits the signal described above using the same physical layer cell ID.

  In addition, resources used by the terminal in order to increase frequency utilization efficiency can be reused depending on the position of the terminal. That is, a terminal having a relatively small influence of interference can transmit the above-described signal using the same resource.

  Alternatively, in order to increase frequency utilization efficiency by spatially reusing frequency resources, the resources used by the terminal can be reused with reference to a transmission / reception point that receives a signal transmitted from the terminal.

  The uplink communication method using multiple transmission / reception points according to an embodiment of the present invention provides a method in which a terminal performs uplink transmission using a virtual cell ID.

  Specifically, the terminal is assigned a virtual cell ID from the base station, applies the assigned virtual cell ID instead of the physical layer cell ID, and some or all uplink channels and signals (eg, PUSCH, PUCCH, etc.). , DMRS, SRS) and transmit the generated signal.

  As described above, in the uplink communication method using multiple transmission / reception points according to an embodiment of the present invention, terminals belonging to transmission / reception points adjacent to each other use different virtual cell IDs, so The effect which can reduce the interference with respect to the received signal can be obtained.

  In addition, it is possible to obtain an effect that each transmission / reception point forms a cell having a unique physical layer cell ID through the uplink transmission method as described above. That is, there is an effect that terminals belonging to different transmission / reception points belonging to the same cell belong to different cells.

  The above-described uplink communication method using multiple transmission / reception points according to an embodiment of the present invention can be introduced into the LTE-Advanced Release-11 standard or a later standard, and is applied to a terminal supporting the standard. Can be applied.

  However, in the case of a terminal that is not assigned a virtual cell ID among terminals that support the LTE-Advanced Release-11 standard or a standard after that, the above-described channel and signal are generated using the physical layer cell ID. can do.

  For example, when a terminal performs initial random access to a cell, a virtual cell ID cannot be assigned. Therefore, a physical layer cell ID can be used for random access message transmission, PUCCH ACK / NAK transmission, and the like.

  Although the present invention has been described with reference to the embodiments, those skilled in the art can make various modifications to the present invention without departing from the spirit and scope of the present invention described in the claims below. It can be understood that modifications and changes can be made.

110 Base station 130 Wide-area transmission / reception point 150 Narrow-area transmission / reception point 151 Transmission / reception point 1
153 Transmission / reception point 2
170 terminal 171 terminal 1
173 Terminal 2

Claims (10)

A method for receiving control data from a transmitter by a terminal,
Receiving a synchronization signal from the transmitter to determine a physical layer cell ID of the transmitter;
Receiving information indicating a virtual cell ID of the transmitter from the transmitter;
Receiving first scrambled control data from the transmitter through a first control channel, wherein the first scrambled control data is scrambled based on the physical layer cell ID of the transmitter; Being stepped,
Receiving second scrambled control data from the transmitter through a second control channel, wherein the second scrambled control data is scrambled based on the virtual cell ID of the transmitter; The second control channel is different from the first control channel; and
A method comprising:   The method of claim 1, wherein the virtual cell ID is different from the physical layer cell ID.   The transmitter according to claim 1, wherein the transmitter belongs to a serving cell, the serving cell comprises another transmitter, and the another transmitter has a virtual cell ID different from the virtual cell ID of the transmitter. Method.   The method of claim 3, wherein the another transmitter has the same physical layer cell ID as the physical layer cell ID of the transmitter.   The method of claim 1, wherein the scrambling sequence is a pseudo-random sequence used for bit-level scrambling.   The method of claim 1, wherein the first scrambled control data comprises a scheduling assignment. A method of transmitting control data to a terminal by a transmitter,
Transmitting information indicating a virtual cell ID of the transmitter to the terminal;
Generating a first scrambling sequence based on the physical layer cell ID of the transmitter;
Scrambling first control data with the first scrambling sequence;
Transmitting the scrambled first control data through a first control channel to the terminal;
Generating a second scrambling sequence based on the virtual cell ID of the transmitter;
Scrambling second control data with the second scrambling sequence;
Transmitting the scrambled second control data to the terminal through a second control channel;
With
The method, wherein the second control channel is different from the first control channel.   The method according to claim 7, wherein the virtual cell ID is different from the physical layer cell ID.   The method of claim 7, wherein the transmitter belongs to a serving cell, the serving cell comprises another transmitter, and the another transmitter has a virtual cell ID that is different from the virtual cell ID of the transmitter.   The method of claim 9, wherein the another transmitter has a physical layer cell ID that is the same as a physical layer cell ID of the transmitter.

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